Consult on heat exchange efficiency
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Dear Haihao friends, there are currently two graphite heat exchangers in the production workshop; they have a diameter of 800 mm and a length of around 3.5 meters. The inlet and outlet for the hot fluid are DN80, while those for the cold fluid are DN100. At present, the piping connections are made using the method shown in Example 1. I believe that since the flow directions of the hot and cold fluids are the same, the heat exchange efficiency is not good. I wonder if modifying it according to Example 2 can improve the heat exchange efficiency Additionally, the diameter of the heat exchanger is 800, and the pipes for the hot fluid inlet and outlet are DN50. Is it possible that within the heat exchanger, the flow velocity of the hot fluid is high at the center, while the flow velocity of the liquid is very low around the periphery? How can this phenomenon be avoided? I hope all fellow sailors will share their opinions! Additionally: Currently, the temperature of the heat exchanger jacket is the same as that of the cold fluid, so no temperature difference can be felt at the inlet and outlet!
Is this graphite heat exchanger of the porous type or tube-type? Graphite has a very high heat transfer rate, and counterflow heat exchange can improve the efficiency of heat transfer； With a DN50 pipe outlet, compared to a diameter of 800, there is no issue of excessive flow velocity at the center and slower flow velocity around it; in other words, the difference is very small ； There is no significant difference between imports and exports; it is necessary to determine whether the flow rate of materials entering and leaving is much higher than what is required
The heat exchanger is of the round-block hole type, with a flow rate of 10 cubic meters per hour, which is the normal required flow rate. If the flow rate decreases and the flow velocity slows down, the heat exchange efficiency will certainly improve, but it will no longer meet the operational requirements
Is the heat transfer effect better in co-current flow than in counter-current flow? It is precisely because the cooling effect does not meet the requirements that we are considering ways to make changes in order to improve the heat exchange efficiency.
The detailed composition of the medium can be provided; in the case of liquid-liquid heat exchange, counterflow is generally better than co-flow. Visually, the area of each unit of this equipment is approximately 60 square meters; a liquid-liquid heat exchanger with a capacity of 10 cubic meters might be on the small side.
Under normal conditions, counterflow heat transfer is better than coflow. If the logarithmic mean temperature is too low or there is temperature crossover, convective heat transfer may not be feasible at all.
Yes, the heat exchange area is 60 square meters, and it is a liquid-liquid heat exchange. Do you mean that the flow rate of 10 cubic meters is too low, or that the heat exchange area is too small?
I guess so; you can discuss the details with me. My phone number is 15962955996